Centralize single quote escaping in src/port/quotes.c

For code-reuse in upcoming functionality in pg_basebackup.

Zoltan Boszormenyi

src/port/quotes.c

@@ -0,0 +1,36 @@
+#include "c.h"
+
+/*
+ * Escape (by doubling) any single quotes or backslashes in given string
+ *
+ * Note: this is used to process postgresql.conf entries and to quote
+ * string literals in pg_basebackup for creating recovery.conf.
+ * Since postgresql.conf strings are defined to treat backslashes as escapes,
+ * we have to double backslashes here.
+ *
+ * Since this function is only used for parsing or creating configuration
+ * files, we do not care about encoding considerations.
+ *
+ * Returns a malloced() string that it's the responsibility of the caller
+ * to free.
+ */
+char *
+escape_single_quotes_ascii(const char *src)
+{
+	int			len = strlen(src),
+				i,
+				j;
+	char	   *result = malloc(len * 2 + 1);
+
+	if (!result)
+		return NULL;
+
+	for (i = 0, j = 0; i < len; i++)
+	{
+		if (SQL_STR_DOUBLE(src[i], true))
+			result[j++] = src[i];
+		result[j++] = src[i];
+	}
+	result[j] = '\0';
+	return result;
+}